Hadi Ravash - Department of Petroleum Engineering, Semnan university, Semnan, Iran
Masoud Nasiri Zarandi - Department of Chemical Engineering, Semnan university, Semnan, Iran

Appropriate use of oil and gas reserves can extend reservoir life and help us to know how to manage these reserves correctly. One of the noticeable facts in reserves management is to take proper methods to protect reservoir, increasing ultimate recovery and try to keep the production rate satisfactory with time.Surfactant flooding is a chemical method which has attracted attentions among researchers. Reducing surface tension of the oil/Brine/grain system is the main mechanism of this method to enhance oil recovery.In the current article we investigated the effects of changing surfactant rate and concentration on ultimate recovery. Analyzing captured photos will help us to measure ultimate residual oil saturation and investigating pore size effect on recovery.Having done the experiments, we concluded that increasing surfactant rate and concentration will both lead to increase ultimate oil recovery. The reason for that can be attributed to the level of surface tension reduction by surfactant and dominating viscous forces to capillary forces in high rates

Porous media, surfactant, micro model, pore structure, viscous force, capillary force